Stimulated emission of sulforhodamine 640 doped DNA distributed feedback (DFB) laser devices

Organic solid thin films of PMMA and surfactant-treated salmon deoxyribonucleic acid (DNA) were used as host materials to dope sulforhodamine (SRh) laser dye. Amplified Spontaneous Emission (ASE) was observed from the dye-doped thin films pumped by frequency-doubled Nd:YAG laser, with DNA host showed a lower ASE pump threshold. Distributed feedback (DFB) laser structures were fabricated on both dye-doped thin films for the 2nd order emission of SRh at 650 nm. Stimulated Emission (Lasing) was obtained by pumping with a doubled Nd:YAG laser at 532 nm. The DNA DFB devices lasing threshold was 30&mgr;J/cm2 or 3.75kW/cm2. The emission linewidth decreased from ~ 30 nm in the ASE mode to < 0.4 nm in the lasing mode. The slope efficiency of the laser emission was ~ 1.2%. Similar emission linewidth change was observed in PMMA DFB devices while the lasing threshold was 53 &mgr;J/cm2 or 6.63kW/cm2 with a slope efficiency of ~0.63%.